Vulvar Vestibulitis Syndrome (VVS), the most common type of chronic vulvo-vaginal pain, negatively impacts the psychological, physical, and reproductive health of approximately 10% of women at some point in their life. Despite decades of research, the etiology and pathophysiology of VVS remain unknown. Current treatments are largely empiric and guided more by an individual clinician's prior experience and comfort level than objective data on therapeutic efficacy. Recent evidence suggests that the etiology of VVS involves impairment of biological and psychological processes, similar to those of other chronic pain disorders. Although women diagnosed with VVS present with a spectrum of mucosal sensitivity, pelvic muscle dysfunction, and psychological distress, the actual diagnosis of VVS continues to rely on relatively crude measures of mucosal sensitivity (cotton swab palpation and patient report of pain) on clinical exam. A lack of strict criteria for evaluation, and dependence on highly subjective measures by both clinician and patient, suggests that this diagnosis is currently poorly circumscribed. As such, it is likely to encompass a heterogeneous, potentially divergent group of women with the sole common feature of frustration with persistent vulvar pain and dyspareunia. Refinement of therapeutic interventions and insight into the underlying pathophysiology of VVS are critically impaired by lack of methods to reliably and reproducibly assess key features of VVS, as well as by the lack of a classification system based on pathophysiological processes. Our long-term goal is to understand the pathogenesis of VVS, so that optimal treatment strategies can be developed. The primary goal of this proposal is to establish the reliability and reproducibility of our recently developed quantitative assessment tools to determine the spectrum of mucosal and pelvic muscle pain sensitivity (Aims 1-2). We will also assess central dysregulation (via experimental pain sensitivity procedures) and psychological factors to provide a solid evidence-based framework for a comprehensive, multiaxial assessment of VVS as a true pain disorder (Aims 3-4). Our rationale is that advances in treatment and potential for prevention of VVS can only be realized in the context of a conceptual framework informed by comprehensive multiaxial assessment of VVS, similar to that of other pain disorders (e.g., temporomandibular disorder, TMD). The public health relevance of this research is that its successful completion will positively impact the physical, psychological and reproductive health of millions of women.